1. Field of the Invention
This invention relates to ink jet recording sheets. More particularly, this invention relates to ink jet recording sheets having improved image waterfastness, and in particular to a paper based recording sheet, which is suitable as a recording sheet for use in an ink jet recording process.
2. Prior Art
Ink jet recording systems using aqueous inks are now well known. These systems usually generate almost no noise and can easily perform multicolour recordings for business, home and commercial printing applications. Recording sheets for ink jet recordings are known. See for example U.S. Pat. Nos. 5,270,103; 5,657,064; 5,760,809; 5,729,266; 4,792,487; 5,405,678; 4,636,409; 4,481,244; 4,496,629; 4,517,244; 5,190,805; 5,320,902; 4,425,405; 4,503,118; 5,163,973; 4,425,405; 5,013,603; 5,397,619; 4,478,910; 5,429,860; 5,457,486; 5,537,137; 5,314,747; 5,474,843; 4,908,240; 5,320,902; 4,740,420; 4,576,867; 4,446,174; 4,830,911; 4,554,181; and 4,877,680.
One aspect of this invention is directed to a recording sheet for use in ink jet printing comprising a substrate having in contact with at least one surface thereof one or more nitrogen containing species. In the preferred embodiments of the invention, the one or more nitrogen containing compounds are in a mixture which also comprises one or more starches, one or more polymer emulsion additives or a combination thereof.
The ink jet recording sheets of this invention exhibit one or more advantages over conventional ink jet printing recording sheets. For example, the ink jet recording sheets of this invention exhibit one or more improved image waterfastness properties. These improve properties include enhanced imagery water resistance to bleed and wet-rub and reduced density loss after exposure to high humidity or in contact with water.
Still another aspect of this invention relates to a process of forming the ink jet recording sheet of this invention which comprises:
(a) applying a liquid composition comprising a volatile liquid such as water, methanol or the like having dissolved or dispersed therein one or more nitrogen containing organic species, preferably a mixture of such species and one or more starches, one or more polymeric emulsion additives or a combination thereof, to a surface of said sheet to form a wetted, treated sheet having said species or said mixture in contact with said surface; and
(b) drying said surface of said wetted, treated sheet to form said ink jet recording sheet.
Yet another aspect of this invention relates to a method of generating images on a surface of an ink recording sheet in an ink jet printing apparatus which comprises:
(a) incorporating the ink jet recording sheet of this invention into said apparatus; and
(b) forming an image on a surface of said sheet treated with said species or said mixture by causing ink to be expelled from said apparatus onto said treated surface of the ink jet recording sheet and to the imaged sheet resulting from such method.